THURSDAY, Aug. 8 (HealthDay News) -- Symptoms of Bell's palsy and stroke can be nearly identical, but emergency doctors were able to identify nearly all patients with Bell's palsy, a new study reveals.

People with Bell's palsy commonly experience partial or complete weakness of the muscles of half of the face, making them unable to raise one eyebrow, wrinkle their foreheads or close one eyelid. Symptoms of Bell's palsy progress fairly rapidly and strongly resemble the symptoms of certain types of stroke.

Bell's palsy affects about 15 of 100,000 people per year. It causes temporary facial paralysis, likely due to damage or trauma to facial nerves.

In this study, researchers analyzed the records of nearly 44,000 patients who were diagnosed with Bell's palsy at emergency departments in California over six years. Ninety days after their ER visit, 0.8 percent of the patients received an alternate diagnosis, such as stroke, brain bleed, brain tumor, central nervous system infection, Guillain-Barre syndrome, Lyme disease, ear infection or shingles.

When narrowed down to alternative diagnoses that were life-threatening, only 0.3 percent of the patients were misdiagnosed with Bell's palsy, according to the study published recently in the Annals of Emergency Medicine.

"Even lacking established guidelines for diagnosing Bell's palsy, which is the most common cause of paralysis of one side of the face, emergency physicians make the right call nearly every time," study lead author Dr. Jahan Fahimi, of Alameda County Medical Center in Oakland, Calif., and the University of California, San Francisco, said in a news release from the American College of Emergency Physicians.

"The dramatic and distressing nature of facial paralysis often brings patients to the ER for evaluation, often with a concern that they are having a stroke. The combination of thorough history-taking and detailed physical exam allows emergency physicians to determine which patients have a dangerous condition and which can safely be discharged home," Fahimi said. "While there may be a role for imaging, such as CT or MRI, the overwhelming majority of patients can be evaluated without advanced diagnostic tests."